Thanks for correcting me about what white noise is.

It is a multi-family dwelling/apartment complex. Neighbors below us and
adjacent to us. No neighbors above, just the roof.

No changes in electrical equipment made the noise go away. It actually
made it more noticeable.

Wind going across a vent pipe seems like the cause. The sound comes and
goes and the pitch does not vary. I first imagined it being a squeaky
iron fan or other piece of equipment on top of the roof. I guess the
sound could be similar to blowing air across the top of an open, empty
bottle.

So, I'm guessing that if it is a vent pipe then I'm out of luck. Can't
block a vent pipe or keep air from going across it. This seems like the
only probable cause given the suggestions presented thus far.

I thought it was ghosts from the past coming to haunt me. Lucky for me,
my wife also could hear the noises.

Jabba

It's not "white noise". White noise has energy spread across the
specturm, not just a single note.

Is this a single family or multi-family dwelling?


Try turning off various circuit breakers and see if you can make it go

away. That will give you a clue.

I was thinking of wind going across a vent pipe, or some airflow
through one of the vents or chimneys. Does the noise say
constant, or does it come and go? Is it always the same pitch,
or does the pitch vary?